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Predictive Study of Trace Metal Pollution of Gold Panning Sites in Birimian Formations: Case of the Yaouré Furrow (Côte d’Ivoire)

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Open Journal of Applied Sciences 2024年第7期14卷 1691-1714页

作者： Tonga Paul Tiemoko Gbele Ouattara Kouassi Ernest Ahoussi Laboratoire des Sciences Gographiques du Gnie Civil et des Gosciences Institut National Polytechnique Flix Houphout-Boigny (INP-HB) Yamoussoukro Cte dIvoire Laboratoiredes Sciences du Sol delEauetdes Gomatriaux Universit Flix Houphout-Boigny (UFHB) Abidjan-Cocody Cte dIvoire

The present study was carried out on small-scale gold mining sites in the Yaouré region of Côte d’Ivoire. This region is geologically representative of the Birimian formations (2.1 Ga) of West Africa. The aim is to determine the potentially toxic trace metals (TMEs) generated by these sites, with a view to preventing possible contamination and/or metal pollution of the waters that provide fish products for local populations. To this end, a sampling campaign was carried out, resulting in the collection of 20 mining waste samples analyzed by X-ray fluorescence spectrometry (XRF) and 10 by X-ray diffractometer (XRD). The XRF analysis detected 06 predominant TMEs: arsenic, chromium, copper, nickel, zinc and vanadium. Statistical analysis was carried out to determine the distributions and correlations between these ETMs. To assess contamination and/or pollution levels, the following indices were calculated on the basis of reference concentrations of upper continental crust MTEs: Enrichment Factor, Geo-accumulation Index, Concentration Factor, Degree of contamination and those related to ecological risks. The results of statistical analyses and indices have shown that arsenic and chromium are the most predominant and can be, depending on the chemical form, potentially more toxic. The results of the DRX analysis show the occurrence of several minerals carrying these two MTEs, especially that of a rare mineral, Stenhuggarite, an arsenic oxide linked to hydrothermal veins. The majority of gold mining operations in West Africa are located in the birimian zone, hence the need for environmental monitoring by the relevant authorities, to prevent potential ecological risks to water and possibly health risks via the food chain.

关键词： Small-Scale Mining Metallic Trace Elements Mining Discharges Contamination Pollution Contamination Pollution Index

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Letter to the Editor: Reverse T3;a Reliable Diagnostic Test for Discerning between Euthyroid Sick and Central Hypothyroidism

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Open Journal of Endocrine and Metabolic Diseases 2024年第2期14卷 73-74页

作者： Udaya M. Kabadi Sarah Exley Broadlawns Medical Center Des Moines Iowa Faulty of Endocrinology Clinic University of Iowa Iowa City Iowa

Letter to the Editor

关键词： Letter ism Sick

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Tribological response of an epoxy matrix filled with graphite and/or carbon nanotubes

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Friction 2017年第2期5卷 171-182页

作者： M.M.SAKKA Z.ANTAR K.ELLEUCH J.F.FELLER Laboratoire de Génie des matériaux et Environnement ENIS Université de Sfax Sfax BP.1173-3038 Tunisia Smart Plastics Group European University of Brittany(UEB) LIMATB-UBS Lorient 56321 France

Reinforced polymer-matrix composites are widely used under sliding contact conditions in various boating and automotive *** this paper,the friction and wear of bulk epoxy and carbon filler reinforced epoxy composites have been investigated using a pin-on-disc *** effect of different fillers on the tribological behavior of an epoxy has been studied using treated and untreated carbon nanotubes,graphite,and a mixture of graphite and carbon *** addition greatly enhances the tribological properties of the epoxy resin,by reducing the friction coefficient and the wear *** addition,it was found that the treated carbon nanotubes/epoxy composites have the best tribological ***,a correlation between contact temperature and friction coefficient is *** the wear mechanisms were determined by scanning electronic microscopy.

关键词： epoxy composites carbon nanotubes wear friction temperature

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Microwave Synthesis of Large Few-Layer Graphene Sheets in Aqueous Solution of Ammonia

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Nano Research 2010年第2期3卷 126-137页

作者： Izabela Janowska Kambiz Chizari Ovidiu Ersen Spyridon Zafeiratos Driss Soubane Victor Da Costa Virginie Speisser Christine Boeglin matthieu Houllé Dominique Bégin Dominique Plee Marc-Jacques Ledoux Cuong Pham-Huu Laboratoire des matériaux Surfaces et Procédés pour la Catalyse(LMSPC)UMR7515 CNRS-Universitéde Strasbourg 25rue Becquerel67087 Strasbourg Cedex 08France Institut de Physique et Chimie des matériaux de Strasbourg(IPCMS) UMR7504 CNRS-Universitéde Strasbourg 23rue du Loess67037 Strasbourg Cedex 02France Arkema Groupement de Recherche de Lacq(GRL)BP 3464170 LACQFrance

Few-layer graphene (FLG) sheets with sizes exceeding several micrometers have been synthesized by exfoliation of expanded graphite in aqueous solution of ammonia under microwave irradiation, with an overall yield approaching 8 wt.%. Transmission electron microscopy (in bright-field and dark-field modes) together with electron diffraction patterns and atomic force microscopy confirmed that this graphene material consisted mostly of mono-, bi- or few-layer graphene (less than ten layers). The high degree of surface reduction was confirmed by X-ray photoelectron and infrared spectroscopies. In addition, the high stability of the FLG in the liquid medium facilitates the deposition of the graphene material onto several substrates via low-cost solution-phase processing techniques, opening the way to subsequent applications of the material.

关键词： Graphene transmission electron microscopy(TEM) expanded graphite exfoliation microwaves

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Flocculation and magnetically-assisted sedimentation of size-sorted beidellite platelets mixed with maghemite nanoparticles

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Nano Research 2020年第11期13卷 3001-3011页

作者： Sofia Housni Sébastien Abramson Jean-Michel Guigner Pierre Levitz Laurent Michot Laboratoire de PHysico-chimie des Electrolytes et Nanosystèmes InterfaciauX(PHENIX UMR 8234 Sorbonne Université-CNRS)Sorbonne UniversitéParis75252France Institut de Minéralogie de Physique des Matériaux et de Cosmochimie(IMPMC UMR 7590Sorbonne Université-IRD-CNRS-MNHN)Sorbonne UniversitéParis75252France

In this study,the flocculation and the subsequent decantation step of mixed suspensions of 10 nm-sizedγ-Fe_(2)O_(3) magnetic nanoparticles and 500 nm-sized beidellite clay platelets was *** work may find application in the field of water treatment,specifically the flocculation processes with magnetically assisted *** a short description of the preparation and characterization of the raw materials(nanoparticles and clays),the influence of several parameters(pH,concentrations of nanoparticles and clays etc.)on the amount of flocculated materials was examined,which gave information on the concentration ranges allowing a complete flocculation,together with a better understanding on the interactions between nanoparticles and clays responsible for *** optimal conditions for magnetically assisted settling were then determined by comparing for each sample sedimentation velocities under gravity and in the presence of a Nd-Fe-B ***,the complex multiscale structure of the flocs in water was explored,through the measurement of several bulk properties(zeta-potential and volume measurements,laser granulometry),while the organization of the materials at a microscopic scale was investigated by cryo-transmission electron microscopy(cryo-TEM)and small-angle X-ray scattering(SAXS).

关键词： magnetic separation nanoparticles clay flocculation decantation characterization

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Case Study for Undetermined Mosquito Species by Polymerase Chain Reaction in Western Burkina Faso

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American Journal of Molecular Biology 2024年第2期14卷 43-53页

作者： Koudraogo Bienvenue Yaméogo Sassan Simplice Kambou Domonbabélé François de Sales Hien Logotio Rachel Angela Traore Franck Adama Yao Rakiswendé Serge Yerbanga centre National de la Recherche Scientifique et Technologique CNRST Institut de Recherche en Sciences de la Sante (IRSS) Laboratoire de recherche sur les maladies infectieuses et parasitaires Bobo-Dioulasso Burkina Faso Institut des Sciences et Techniques (INSTech Bobo) Avenue de Sya Bobo-Dioulasso Burkina Faso

Introduction: Malaria eradication campaigns all over the world are largely based on parasite and vector control. Vector identification, whether morphological or molecular, is an essential component of vector control. This study analyzed the possible causes of indeterminate polymerase chain reaction (PCR) results for mosquito species in Western part of Burkina Faso. Methodology: From July 2021 to November 2021, mosquitoes were collected during the period of high malaria transmission in the village of Séguéré, Houet province, Burkina Faso, and morphologically identified. After DNA extraction, samples were amplified by sine 200× PCR to identify species of the Anopheles gambiae complex. Indeterminate samples were then selected for further analysis. The parameters studied were: DNA dilution, the effect of protocol adjusting, and the type of protocol used. Results: A total of 130 “indeterminate” DNAs diluted 1:10 were analyzed. After dilution, the mean amount was 14.73 ± 3.59 ng/μL and absorbance 1.71 ± 0.1. PCR chain reaction yielded 94.62% (123/130) anopheline species in SINE PCR, 5.38% (7/130) “negative”. A significant difference between SINE PCR before dilution and after dilution was observed (P < 0.001). Identification tests carried out using other protocols gave no positive results. From these results, we note that the adaptation of the protocol significantly reduced the polymerase amplification results of the species. Conclusion: It is therefore necessary to respect the amplification protocols. However, the persistence of “indeterminate” results suggests that further studies should be carried out to shed more light on the subject.

关键词： Malaria Vector DNA PCR

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The Effects of Accelerated Photooxidation on Molecular Weight and Thermal and Mechanical Properties of PHBV/Cloisite 30B Bionanocomposites

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Journal of Renewable materials 2018年第3期6卷 288-298页

作者： Kahina Iggui Mustapha Kaci Nicolas Le Moigne Anne Bergeret centre des matériaux des Mines d’Alès(C2MA) IMT Mines AlesUniversitéde Montpellier30100 AlèsFrance Laboratory of Advanced Polymer materials University of BéjaïaBéjaïa Province06000Algeria Institut de Technologie UniversitéAkli Mohand OulhadjBouira 10000Algeria

The effects of accelerated photooxidation on the molecular weight and thermal and mechanical properties of Cast PHBV and PHBV/Cloisite 30B(3 wt%)bionanocomposites are investigated *** size exclusion chromatography(SEC)analysis,a significant decrease in both weight and number average molecular weights was observed for all irradiated samples over time,resulting from the chain scission *** scanning calorimetry(DSC)data indicated a decrease in degree of crystallinity and melting temperature after UV exposure,with the appearance of double melting peaks related to the changes in the crystal structure of *** stability,tensile and thermo-mechanical properties were also reduced consecutively in photooxidation,being more pronounced for Cast *** study shows that the incorporation of Cloisite 30B in PHBV provides a better resistance to photooxidation in comparison with the neat polymer.

关键词： Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) organo-modified montmorillonite bionanocomposites accelerated photooxidation and degradation

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3D hydrodynamics involving multiple eccentric impellers in unbaffled cylindrical tank

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Chinese Journal of Chemical Engineering 2016年第5期24卷 572-580页

作者： Houari Ameur Institut des Sciences et Technologies Centre Universitaire Salhi Ahmed CUN-SA

In this paper, the numerical predictions of 3D hydrodynamics and power consumption in a vessel stirred by mul- tiple eccentrically located impellers are presented. The vessel is a fiat-bottomed cylindrical one equipped with six-curved bladed impellers. Aqueous solutions of xanthan gum are used, which have a shear thinning behavior with yield stress. The influence of several parameters on the mixing efficiency has been investigated, namely： the stirring rate, fluid theology, impeller number and impeller clearance from the tank bottom. Our predicted results are compared with other experimental data and a satisfactory agreement is found.

关键词： Computational fluid dynamics Mixing Non-Newtonian fluids Laminar flow Eccentric impeller

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Synthesis,structural and dielectric properties of Ho-doped SrBi_2Nb_2O_9 prepared by Co-precipitation method

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Science China materials 2016年第11期59卷 921-926页

作者： Mohamed Afqir Amina Tachafine Didier Fasquelle Mohamed Elaatmani Jean-Claude Carru Abdelouahad Zegzouti Mohamed Daoud Laboratoire des Sciences des matériaux Inorganiques et leurs Applications Facultédes Sciences SemlaliaUniversitéCadi AyyadMarrakechMaroc Unitéde Dynamique et Structure des matériaux Moléculaires Universitédu Littoral Côte d’OpaleCalaisFrance

This paper reported the synthesis of Ho-doped SBN(SrBi_(2-x)Ho_xNb_2O_9:x = 0 and 0.4) by a co-precipitation method and investigated the synthesized material with X-ray diffraction analyses,infrared spectroscopy,and electrical *** results show that the Ho-doped SBN has low loss values at higher frequencies and the flattening of dielectric constant which are very desirable in nonvolatile ferroelectric random access memory applications.

关键词： Co-precipitation XRD FTIR Dielectric properties

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Natural frequencies of composite beams with a variable fiber volume fraction including rotary inertia and shear deformation

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Applied mathematics and Mechanics(English Edition) 2009年第6期30卷 717-726页

作者： Y. Bedjilili A. Tounsi H. M. Berrabah I. Mechab E. A. Adda Bedia S. Benaissa Université de Tlemcen Faculté des Sciences de l'ingénieurDépartement de Génie MécaniqueAlgérie Laboratoire des matériaux et Hydrologie Université de Sidi Bel AbbesAlgérie Laboratoire de mathématiques Université de Sidi Bel AbbesAlgérie

The present study is concerned with the vibration analysis of symmetric composite beams with a variable fiber volume fraction through thickness. First-order shear deformation and rotary inertia have been included in the analysis. The solution procedure is applicable to arbitrary boundary conditions. Continuous gradation of the fiber volume fraction is modeled in the form of an m-th power polynomial of the coordinate axis in the thickness direction of the beam. By varying the fiber volume fraction within the symmetric composite beam to create a functionally graded material （FGM）, certain vibration characteristics are affected. Results are presented to demonstrate the effects of shear deformation, fiber volume fraction, and boundary conditions on the natural frequencies and mode shapes of composite beams.

关键词： free vibration functionally graded materials first-order shear deformationtheory

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